1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2012 Red Hat, Inc. 4 * 5 * Author: Mikulas Patocka <mpatocka@redhat.com> 6 * 7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors 8 * 9 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set 10 * default prefetch value. Data are read in "prefetch_cluster" chunks from the 11 * hash device. Setting this greatly improves performance when data and hash 12 * are on the same disk on different partitions on devices with poor random 13 * access behavior. 14 */ 15 16 #include "dm-verity.h" 17 #include "dm-verity-fec.h" 18 #include "dm-verity-verify-sig.h" 19 #include <linux/module.h> 20 #include <linux/reboot.h> 21 22 #define DM_MSG_PREFIX "verity" 23 24 #define DM_VERITY_ENV_LENGTH 42 25 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 26 27 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 28 29 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 30 31 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 32 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 33 #define DM_VERITY_OPT_PANIC "panic_on_corruption" 34 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 35 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 36 37 #define DM_VERITY_OPTS_MAX (3 + DM_VERITY_OPTS_FEC + \ 38 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 39 40 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 41 42 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); 43 44 struct dm_verity_prefetch_work { 45 struct work_struct work; 46 struct dm_verity *v; 47 sector_t block; 48 unsigned n_blocks; 49 }; 50 51 /* 52 * Auxiliary structure appended to each dm-bufio buffer. If the value 53 * hash_verified is nonzero, hash of the block has been verified. 54 * 55 * The variable hash_verified is set to 0 when allocating the buffer, then 56 * it can be changed to 1 and it is never reset to 0 again. 57 * 58 * There is no lock around this value, a race condition can at worst cause 59 * that multiple processes verify the hash of the same buffer simultaneously 60 * and write 1 to hash_verified simultaneously. 61 * This condition is harmless, so we don't need locking. 62 */ 63 struct buffer_aux { 64 int hash_verified; 65 }; 66 67 /* 68 * Initialize struct buffer_aux for a freshly created buffer. 69 */ 70 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 71 { 72 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 73 74 aux->hash_verified = 0; 75 } 76 77 /* 78 * Translate input sector number to the sector number on the target device. 79 */ 80 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 81 { 82 return v->data_start + dm_target_offset(v->ti, bi_sector); 83 } 84 85 /* 86 * Return hash position of a specified block at a specified tree level 87 * (0 is the lowest level). 88 * The lowest "hash_per_block_bits"-bits of the result denote hash position 89 * inside a hash block. The remaining bits denote location of the hash block. 90 */ 91 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 92 int level) 93 { 94 return block >> (level * v->hash_per_block_bits); 95 } 96 97 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, 98 const u8 *data, size_t len, 99 struct crypto_wait *wait) 100 { 101 struct scatterlist sg; 102 103 if (likely(!is_vmalloc_addr(data))) { 104 sg_init_one(&sg, data, len); 105 ahash_request_set_crypt(req, &sg, NULL, len); 106 return crypto_wait_req(crypto_ahash_update(req), wait); 107 } else { 108 do { 109 int r; 110 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 111 flush_kernel_vmap_range((void *)data, this_step); 112 sg_init_table(&sg, 1); 113 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 114 ahash_request_set_crypt(req, &sg, NULL, this_step); 115 r = crypto_wait_req(crypto_ahash_update(req), wait); 116 if (unlikely(r)) 117 return r; 118 data += this_step; 119 len -= this_step; 120 } while (len); 121 return 0; 122 } 123 } 124 125 /* 126 * Wrapper for crypto_ahash_init, which handles verity salting. 127 */ 128 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req, 129 struct crypto_wait *wait) 130 { 131 int r; 132 133 ahash_request_set_tfm(req, v->tfm); 134 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | 135 CRYPTO_TFM_REQ_MAY_BACKLOG, 136 crypto_req_done, (void *)wait); 137 crypto_init_wait(wait); 138 139 r = crypto_wait_req(crypto_ahash_init(req), wait); 140 141 if (unlikely(r < 0)) { 142 DMERR("crypto_ahash_init failed: %d", r); 143 return r; 144 } 145 146 if (likely(v->salt_size && (v->version >= 1))) 147 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 148 149 return r; 150 } 151 152 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, 153 u8 *digest, struct crypto_wait *wait) 154 { 155 int r; 156 157 if (unlikely(v->salt_size && (!v->version))) { 158 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 159 160 if (r < 0) { 161 DMERR("verity_hash_final failed updating salt: %d", r); 162 goto out; 163 } 164 } 165 166 ahash_request_set_crypt(req, NULL, digest, 0); 167 r = crypto_wait_req(crypto_ahash_final(req), wait); 168 out: 169 return r; 170 } 171 172 int verity_hash(struct dm_verity *v, struct ahash_request *req, 173 const u8 *data, size_t len, u8 *digest) 174 { 175 int r; 176 struct crypto_wait wait; 177 178 r = verity_hash_init(v, req, &wait); 179 if (unlikely(r < 0)) 180 goto out; 181 182 r = verity_hash_update(v, req, data, len, &wait); 183 if (unlikely(r < 0)) 184 goto out; 185 186 r = verity_hash_final(v, req, digest, &wait); 187 188 out: 189 return r; 190 } 191 192 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 193 sector_t *hash_block, unsigned *offset) 194 { 195 sector_t position = verity_position_at_level(v, block, level); 196 unsigned idx; 197 198 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 199 200 if (!offset) 201 return; 202 203 idx = position & ((1 << v->hash_per_block_bits) - 1); 204 if (!v->version) 205 *offset = idx * v->digest_size; 206 else 207 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 208 } 209 210 /* 211 * Handle verification errors. 212 */ 213 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 214 unsigned long long block) 215 { 216 char verity_env[DM_VERITY_ENV_LENGTH]; 217 char *envp[] = { verity_env, NULL }; 218 const char *type_str = ""; 219 struct mapped_device *md = dm_table_get_md(v->ti->table); 220 221 /* Corruption should be visible in device status in all modes */ 222 v->hash_failed = 1; 223 224 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 225 goto out; 226 227 v->corrupted_errs++; 228 229 switch (type) { 230 case DM_VERITY_BLOCK_TYPE_DATA: 231 type_str = "data"; 232 break; 233 case DM_VERITY_BLOCK_TYPE_METADATA: 234 type_str = "metadata"; 235 break; 236 default: 237 BUG(); 238 } 239 240 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 241 type_str, block); 242 243 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) 244 DMERR("%s: reached maximum errors", v->data_dev->name); 245 246 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 247 DM_VERITY_ENV_VAR_NAME, type, block); 248 249 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 250 251 out: 252 if (v->mode == DM_VERITY_MODE_LOGGING) 253 return 0; 254 255 if (v->mode == DM_VERITY_MODE_RESTART) 256 kernel_restart("dm-verity device corrupted"); 257 258 if (v->mode == DM_VERITY_MODE_PANIC) 259 panic("dm-verity device corrupted"); 260 261 return 1; 262 } 263 264 /* 265 * Verify hash of a metadata block pertaining to the specified data block 266 * ("block" argument) at a specified level ("level" argument). 267 * 268 * On successful return, verity_io_want_digest(v, io) contains the hash value 269 * for a lower tree level or for the data block (if we're at the lowest level). 270 * 271 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 272 * If "skip_unverified" is false, unverified buffer is hashed and verified 273 * against current value of verity_io_want_digest(v, io). 274 */ 275 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 276 sector_t block, int level, bool skip_unverified, 277 u8 *want_digest) 278 { 279 struct dm_buffer *buf; 280 struct buffer_aux *aux; 281 u8 *data; 282 int r; 283 sector_t hash_block; 284 unsigned offset; 285 286 verity_hash_at_level(v, block, level, &hash_block, &offset); 287 288 data = dm_bufio_read(v->bufio, hash_block, &buf); 289 if (IS_ERR(data)) 290 return PTR_ERR(data); 291 292 aux = dm_bufio_get_aux_data(buf); 293 294 if (!aux->hash_verified) { 295 if (skip_unverified) { 296 r = 1; 297 goto release_ret_r; 298 } 299 300 r = verity_hash(v, verity_io_hash_req(v, io), 301 data, 1 << v->hash_dev_block_bits, 302 verity_io_real_digest(v, io)); 303 if (unlikely(r < 0)) 304 goto release_ret_r; 305 306 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 307 v->digest_size) == 0)) 308 aux->hash_verified = 1; 309 else if (verity_fec_decode(v, io, 310 DM_VERITY_BLOCK_TYPE_METADATA, 311 hash_block, data, NULL) == 0) 312 aux->hash_verified = 1; 313 else if (verity_handle_err(v, 314 DM_VERITY_BLOCK_TYPE_METADATA, 315 hash_block)) { 316 r = -EIO; 317 goto release_ret_r; 318 } 319 } 320 321 data += offset; 322 memcpy(want_digest, data, v->digest_size); 323 r = 0; 324 325 release_ret_r: 326 dm_bufio_release(buf); 327 return r; 328 } 329 330 /* 331 * Find a hash for a given block, write it to digest and verify the integrity 332 * of the hash tree if necessary. 333 */ 334 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 335 sector_t block, u8 *digest, bool *is_zero) 336 { 337 int r = 0, i; 338 339 if (likely(v->levels)) { 340 /* 341 * First, we try to get the requested hash for 342 * the current block. If the hash block itself is 343 * verified, zero is returned. If it isn't, this 344 * function returns 1 and we fall back to whole 345 * chain verification. 346 */ 347 r = verity_verify_level(v, io, block, 0, true, digest); 348 if (likely(r <= 0)) 349 goto out; 350 } 351 352 memcpy(digest, v->root_digest, v->digest_size); 353 354 for (i = v->levels - 1; i >= 0; i--) { 355 r = verity_verify_level(v, io, block, i, false, digest); 356 if (unlikely(r)) 357 goto out; 358 } 359 out: 360 if (!r && v->zero_digest) 361 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 362 else 363 *is_zero = false; 364 365 return r; 366 } 367 368 /* 369 * Calculates the digest for the given bio 370 */ 371 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 372 struct bvec_iter *iter, struct crypto_wait *wait) 373 { 374 unsigned int todo = 1 << v->data_dev_block_bits; 375 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 376 struct scatterlist sg; 377 struct ahash_request *req = verity_io_hash_req(v, io); 378 379 do { 380 int r; 381 unsigned int len; 382 struct bio_vec bv = bio_iter_iovec(bio, *iter); 383 384 sg_init_table(&sg, 1); 385 386 len = bv.bv_len; 387 388 if (likely(len >= todo)) 389 len = todo; 390 /* 391 * Operating on a single page at a time looks suboptimal 392 * until you consider the typical block size is 4,096B. 393 * Going through this loops twice should be very rare. 394 */ 395 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 396 ahash_request_set_crypt(req, &sg, NULL, len); 397 r = crypto_wait_req(crypto_ahash_update(req), wait); 398 399 if (unlikely(r < 0)) { 400 DMERR("verity_for_io_block crypto op failed: %d", r); 401 return r; 402 } 403 404 bio_advance_iter(bio, iter, len); 405 todo -= len; 406 } while (todo); 407 408 return 0; 409 } 410 411 /* 412 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 413 * starting from iter. 414 */ 415 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 416 struct bvec_iter *iter, 417 int (*process)(struct dm_verity *v, 418 struct dm_verity_io *io, u8 *data, 419 size_t len)) 420 { 421 unsigned todo = 1 << v->data_dev_block_bits; 422 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 423 424 do { 425 int r; 426 u8 *page; 427 unsigned len; 428 struct bio_vec bv = bio_iter_iovec(bio, *iter); 429 430 page = kmap_atomic(bv.bv_page); 431 len = bv.bv_len; 432 433 if (likely(len >= todo)) 434 len = todo; 435 436 r = process(v, io, page + bv.bv_offset, len); 437 kunmap_atomic(page); 438 439 if (r < 0) 440 return r; 441 442 bio_advance_iter(bio, iter, len); 443 todo -= len; 444 } while (todo); 445 446 return 0; 447 } 448 449 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 450 u8 *data, size_t len) 451 { 452 memset(data, 0, len); 453 return 0; 454 } 455 456 /* 457 * Moves the bio iter one data block forward. 458 */ 459 static inline void verity_bv_skip_block(struct dm_verity *v, 460 struct dm_verity_io *io, 461 struct bvec_iter *iter) 462 { 463 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 464 465 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 466 } 467 468 /* 469 * Verify one "dm_verity_io" structure. 470 */ 471 static int verity_verify_io(struct dm_verity_io *io) 472 { 473 bool is_zero; 474 struct dm_verity *v = io->v; 475 struct bvec_iter start; 476 unsigned b; 477 struct crypto_wait wait; 478 479 for (b = 0; b < io->n_blocks; b++) { 480 int r; 481 sector_t cur_block = io->block + b; 482 struct ahash_request *req = verity_io_hash_req(v, io); 483 484 if (v->validated_blocks && 485 likely(test_bit(cur_block, v->validated_blocks))) { 486 verity_bv_skip_block(v, io, &io->iter); 487 continue; 488 } 489 490 r = verity_hash_for_block(v, io, cur_block, 491 verity_io_want_digest(v, io), 492 &is_zero); 493 if (unlikely(r < 0)) 494 return r; 495 496 if (is_zero) { 497 /* 498 * If we expect a zero block, don't validate, just 499 * return zeros. 500 */ 501 r = verity_for_bv_block(v, io, &io->iter, 502 verity_bv_zero); 503 if (unlikely(r < 0)) 504 return r; 505 506 continue; 507 } 508 509 r = verity_hash_init(v, req, &wait); 510 if (unlikely(r < 0)) 511 return r; 512 513 start = io->iter; 514 r = verity_for_io_block(v, io, &io->iter, &wait); 515 if (unlikely(r < 0)) 516 return r; 517 518 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 519 &wait); 520 if (unlikely(r < 0)) 521 return r; 522 523 if (likely(memcmp(verity_io_real_digest(v, io), 524 verity_io_want_digest(v, io), v->digest_size) == 0)) { 525 if (v->validated_blocks) 526 set_bit(cur_block, v->validated_blocks); 527 continue; 528 } 529 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 530 cur_block, NULL, &start) == 0) 531 continue; 532 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 533 cur_block)) 534 return -EIO; 535 } 536 537 return 0; 538 } 539 540 /* 541 * Skip verity work in response to I/O error when system is shutting down. 542 */ 543 static inline bool verity_is_system_shutting_down(void) 544 { 545 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 546 || system_state == SYSTEM_RESTART; 547 } 548 549 /* 550 * End one "io" structure with a given error. 551 */ 552 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 553 { 554 struct dm_verity *v = io->v; 555 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 556 557 bio->bi_end_io = io->orig_bi_end_io; 558 bio->bi_status = status; 559 560 verity_fec_finish_io(io); 561 562 bio_endio(bio); 563 } 564 565 static void verity_work(struct work_struct *w) 566 { 567 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 568 569 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 570 } 571 572 static void verity_end_io(struct bio *bio) 573 { 574 struct dm_verity_io *io = bio->bi_private; 575 576 if (bio->bi_status && 577 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) { 578 verity_finish_io(io, bio->bi_status); 579 return; 580 } 581 582 INIT_WORK(&io->work, verity_work); 583 queue_work(io->v->verify_wq, &io->work); 584 } 585 586 /* 587 * Prefetch buffers for the specified io. 588 * The root buffer is not prefetched, it is assumed that it will be cached 589 * all the time. 590 */ 591 static void verity_prefetch_io(struct work_struct *work) 592 { 593 struct dm_verity_prefetch_work *pw = 594 container_of(work, struct dm_verity_prefetch_work, work); 595 struct dm_verity *v = pw->v; 596 int i; 597 598 for (i = v->levels - 2; i >= 0; i--) { 599 sector_t hash_block_start; 600 sector_t hash_block_end; 601 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 602 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 603 if (!i) { 604 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster); 605 606 cluster >>= v->data_dev_block_bits; 607 if (unlikely(!cluster)) 608 goto no_prefetch_cluster; 609 610 if (unlikely(cluster & (cluster - 1))) 611 cluster = 1 << __fls(cluster); 612 613 hash_block_start &= ~(sector_t)(cluster - 1); 614 hash_block_end |= cluster - 1; 615 if (unlikely(hash_block_end >= v->hash_blocks)) 616 hash_block_end = v->hash_blocks - 1; 617 } 618 no_prefetch_cluster: 619 dm_bufio_prefetch(v->bufio, hash_block_start, 620 hash_block_end - hash_block_start + 1); 621 } 622 623 kfree(pw); 624 } 625 626 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 627 { 628 sector_t block = io->block; 629 unsigned int n_blocks = io->n_blocks; 630 struct dm_verity_prefetch_work *pw; 631 632 if (v->validated_blocks) { 633 while (n_blocks && test_bit(block, v->validated_blocks)) { 634 block++; 635 n_blocks--; 636 } 637 while (n_blocks && test_bit(block + n_blocks - 1, 638 v->validated_blocks)) 639 n_blocks--; 640 if (!n_blocks) 641 return; 642 } 643 644 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 645 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 646 647 if (!pw) 648 return; 649 650 INIT_WORK(&pw->work, verity_prefetch_io); 651 pw->v = v; 652 pw->block = block; 653 pw->n_blocks = n_blocks; 654 queue_work(v->verify_wq, &pw->work); 655 } 656 657 /* 658 * Bio map function. It allocates dm_verity_io structure and bio vector and 659 * fills them. Then it issues prefetches and the I/O. 660 */ 661 static int verity_map(struct dm_target *ti, struct bio *bio) 662 { 663 struct dm_verity *v = ti->private; 664 struct dm_verity_io *io; 665 666 bio_set_dev(bio, v->data_dev->bdev); 667 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 668 669 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & 670 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 671 DMERR_LIMIT("unaligned io"); 672 return DM_MAPIO_KILL; 673 } 674 675 if (bio_end_sector(bio) >> 676 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 677 DMERR_LIMIT("io out of range"); 678 return DM_MAPIO_KILL; 679 } 680 681 if (bio_data_dir(bio) == WRITE) 682 return DM_MAPIO_KILL; 683 684 io = dm_per_bio_data(bio, ti->per_io_data_size); 685 io->v = v; 686 io->orig_bi_end_io = bio->bi_end_io; 687 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 688 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 689 690 bio->bi_end_io = verity_end_io; 691 bio->bi_private = io; 692 io->iter = bio->bi_iter; 693 694 verity_fec_init_io(io); 695 696 verity_submit_prefetch(v, io); 697 698 submit_bio_noacct(bio); 699 700 return DM_MAPIO_SUBMITTED; 701 } 702 703 /* 704 * Status: V (valid) or C (corruption found) 705 */ 706 static void verity_status(struct dm_target *ti, status_type_t type, 707 unsigned status_flags, char *result, unsigned maxlen) 708 { 709 struct dm_verity *v = ti->private; 710 unsigned args = 0; 711 unsigned sz = 0; 712 unsigned x; 713 714 switch (type) { 715 case STATUSTYPE_INFO: 716 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 717 break; 718 case STATUSTYPE_TABLE: 719 DMEMIT("%u %s %s %u %u %llu %llu %s ", 720 v->version, 721 v->data_dev->name, 722 v->hash_dev->name, 723 1 << v->data_dev_block_bits, 724 1 << v->hash_dev_block_bits, 725 (unsigned long long)v->data_blocks, 726 (unsigned long long)v->hash_start, 727 v->alg_name 728 ); 729 for (x = 0; x < v->digest_size; x++) 730 DMEMIT("%02x", v->root_digest[x]); 731 DMEMIT(" "); 732 if (!v->salt_size) 733 DMEMIT("-"); 734 else 735 for (x = 0; x < v->salt_size; x++) 736 DMEMIT("%02x", v->salt[x]); 737 if (v->mode != DM_VERITY_MODE_EIO) 738 args++; 739 if (verity_fec_is_enabled(v)) 740 args += DM_VERITY_OPTS_FEC; 741 if (v->zero_digest) 742 args++; 743 if (v->validated_blocks) 744 args++; 745 if (v->signature_key_desc) 746 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 747 if (!args) 748 return; 749 DMEMIT(" %u", args); 750 if (v->mode != DM_VERITY_MODE_EIO) { 751 DMEMIT(" "); 752 switch (v->mode) { 753 case DM_VERITY_MODE_LOGGING: 754 DMEMIT(DM_VERITY_OPT_LOGGING); 755 break; 756 case DM_VERITY_MODE_RESTART: 757 DMEMIT(DM_VERITY_OPT_RESTART); 758 break; 759 case DM_VERITY_MODE_PANIC: 760 DMEMIT(DM_VERITY_OPT_PANIC); 761 break; 762 default: 763 BUG(); 764 } 765 } 766 if (v->zero_digest) 767 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 768 if (v->validated_blocks) 769 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 770 sz = verity_fec_status_table(v, sz, result, maxlen); 771 if (v->signature_key_desc) 772 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 773 " %s", v->signature_key_desc); 774 break; 775 } 776 } 777 778 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 779 { 780 struct dm_verity *v = ti->private; 781 782 *bdev = v->data_dev->bdev; 783 784 if (v->data_start || 785 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) 786 return 1; 787 return 0; 788 } 789 790 static int verity_iterate_devices(struct dm_target *ti, 791 iterate_devices_callout_fn fn, void *data) 792 { 793 struct dm_verity *v = ti->private; 794 795 return fn(ti, v->data_dev, v->data_start, ti->len, data); 796 } 797 798 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 799 { 800 struct dm_verity *v = ti->private; 801 802 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 803 limits->logical_block_size = 1 << v->data_dev_block_bits; 804 805 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 806 limits->physical_block_size = 1 << v->data_dev_block_bits; 807 808 blk_limits_io_min(limits, limits->logical_block_size); 809 } 810 811 static void verity_dtr(struct dm_target *ti) 812 { 813 struct dm_verity *v = ti->private; 814 815 if (v->verify_wq) 816 destroy_workqueue(v->verify_wq); 817 818 if (v->bufio) 819 dm_bufio_client_destroy(v->bufio); 820 821 kvfree(v->validated_blocks); 822 kfree(v->salt); 823 kfree(v->root_digest); 824 kfree(v->zero_digest); 825 826 if (v->tfm) 827 crypto_free_ahash(v->tfm); 828 829 kfree(v->alg_name); 830 831 if (v->hash_dev) 832 dm_put_device(ti, v->hash_dev); 833 834 if (v->data_dev) 835 dm_put_device(ti, v->data_dev); 836 837 verity_fec_dtr(v); 838 839 kfree(v->signature_key_desc); 840 841 kfree(v); 842 } 843 844 static int verity_alloc_most_once(struct dm_verity *v) 845 { 846 struct dm_target *ti = v->ti; 847 848 /* the bitset can only handle INT_MAX blocks */ 849 if (v->data_blocks > INT_MAX) { 850 ti->error = "device too large to use check_at_most_once"; 851 return -E2BIG; 852 } 853 854 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 855 sizeof(unsigned long), 856 GFP_KERNEL); 857 if (!v->validated_blocks) { 858 ti->error = "failed to allocate bitset for check_at_most_once"; 859 return -ENOMEM; 860 } 861 862 return 0; 863 } 864 865 static int verity_alloc_zero_digest(struct dm_verity *v) 866 { 867 int r = -ENOMEM; 868 struct ahash_request *req; 869 u8 *zero_data; 870 871 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 872 873 if (!v->zero_digest) 874 return r; 875 876 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 877 878 if (!req) 879 return r; /* verity_dtr will free zero_digest */ 880 881 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 882 883 if (!zero_data) 884 goto out; 885 886 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 887 v->zero_digest); 888 889 out: 890 kfree(req); 891 kfree(zero_data); 892 893 return r; 894 } 895 896 static inline bool verity_is_verity_mode(const char *arg_name) 897 { 898 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 899 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 900 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 901 } 902 903 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 904 { 905 if (v->mode) 906 return -EINVAL; 907 908 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 909 v->mode = DM_VERITY_MODE_LOGGING; 910 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 911 v->mode = DM_VERITY_MODE_RESTART; 912 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 913 v->mode = DM_VERITY_MODE_PANIC; 914 915 return 0; 916 } 917 918 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 919 struct dm_verity_sig_opts *verify_args) 920 { 921 int r; 922 unsigned argc; 923 struct dm_target *ti = v->ti; 924 const char *arg_name; 925 926 static const struct dm_arg _args[] = { 927 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 928 }; 929 930 r = dm_read_arg_group(_args, as, &argc, &ti->error); 931 if (r) 932 return -EINVAL; 933 934 if (!argc) 935 return 0; 936 937 do { 938 arg_name = dm_shift_arg(as); 939 argc--; 940 941 if (verity_is_verity_mode(arg_name)) { 942 r = verity_parse_verity_mode(v, arg_name); 943 if (r) { 944 ti->error = "Conflicting error handling parameters"; 945 return r; 946 } 947 continue; 948 949 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 950 r = verity_alloc_zero_digest(v); 951 if (r) { 952 ti->error = "Cannot allocate zero digest"; 953 return r; 954 } 955 continue; 956 957 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 958 r = verity_alloc_most_once(v); 959 if (r) 960 return r; 961 continue; 962 963 } else if (verity_is_fec_opt_arg(arg_name)) { 964 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 965 if (r) 966 return r; 967 continue; 968 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 969 r = verity_verify_sig_parse_opt_args(as, v, 970 verify_args, 971 &argc, arg_name); 972 if (r) 973 return r; 974 continue; 975 976 } 977 978 ti->error = "Unrecognized verity feature request"; 979 return -EINVAL; 980 } while (argc && !r); 981 982 return r; 983 } 984 985 /* 986 * Target parameters: 987 * <version> The current format is version 1. 988 * Vsn 0 is compatible with original Chromium OS releases. 989 * <data device> 990 * <hash device> 991 * <data block size> 992 * <hash block size> 993 * <the number of data blocks> 994 * <hash start block> 995 * <algorithm> 996 * <digest> 997 * <salt> Hex string or "-" if no salt. 998 */ 999 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) 1000 { 1001 struct dm_verity *v; 1002 struct dm_verity_sig_opts verify_args = {0}; 1003 struct dm_arg_set as; 1004 unsigned int num; 1005 unsigned long long num_ll; 1006 int r; 1007 int i; 1008 sector_t hash_position; 1009 char dummy; 1010 char *root_hash_digest_to_validate; 1011 1012 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1013 if (!v) { 1014 ti->error = "Cannot allocate verity structure"; 1015 return -ENOMEM; 1016 } 1017 ti->private = v; 1018 v->ti = ti; 1019 1020 r = verity_fec_ctr_alloc(v); 1021 if (r) 1022 goto bad; 1023 1024 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { 1025 ti->error = "Device must be readonly"; 1026 r = -EINVAL; 1027 goto bad; 1028 } 1029 1030 if (argc < 10) { 1031 ti->error = "Not enough arguments"; 1032 r = -EINVAL; 1033 goto bad; 1034 } 1035 1036 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1037 num > 1) { 1038 ti->error = "Invalid version"; 1039 r = -EINVAL; 1040 goto bad; 1041 } 1042 v->version = num; 1043 1044 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); 1045 if (r) { 1046 ti->error = "Data device lookup failed"; 1047 goto bad; 1048 } 1049 1050 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); 1051 if (r) { 1052 ti->error = "Hash device lookup failed"; 1053 goto bad; 1054 } 1055 1056 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1057 !num || (num & (num - 1)) || 1058 num < bdev_logical_block_size(v->data_dev->bdev) || 1059 num > PAGE_SIZE) { 1060 ti->error = "Invalid data device block size"; 1061 r = -EINVAL; 1062 goto bad; 1063 } 1064 v->data_dev_block_bits = __ffs(num); 1065 1066 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1067 !num || (num & (num - 1)) || 1068 num < bdev_logical_block_size(v->hash_dev->bdev) || 1069 num > INT_MAX) { 1070 ti->error = "Invalid hash device block size"; 1071 r = -EINVAL; 1072 goto bad; 1073 } 1074 v->hash_dev_block_bits = __ffs(num); 1075 1076 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1077 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1078 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1079 ti->error = "Invalid data blocks"; 1080 r = -EINVAL; 1081 goto bad; 1082 } 1083 v->data_blocks = num_ll; 1084 1085 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1086 ti->error = "Data device is too small"; 1087 r = -EINVAL; 1088 goto bad; 1089 } 1090 1091 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1092 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1093 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1094 ti->error = "Invalid hash start"; 1095 r = -EINVAL; 1096 goto bad; 1097 } 1098 v->hash_start = num_ll; 1099 1100 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1101 if (!v->alg_name) { 1102 ti->error = "Cannot allocate algorithm name"; 1103 r = -ENOMEM; 1104 goto bad; 1105 } 1106 1107 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0); 1108 if (IS_ERR(v->tfm)) { 1109 ti->error = "Cannot initialize hash function"; 1110 r = PTR_ERR(v->tfm); 1111 v->tfm = NULL; 1112 goto bad; 1113 } 1114 1115 /* 1116 * dm-verity performance can vary greatly depending on which hash 1117 * algorithm implementation is used. Help people debug performance 1118 * problems by logging the ->cra_driver_name. 1119 */ 1120 DMINFO("%s using implementation \"%s\"", v->alg_name, 1121 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1122 1123 v->digest_size = crypto_ahash_digestsize(v->tfm); 1124 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1125 ti->error = "Digest size too big"; 1126 r = -EINVAL; 1127 goto bad; 1128 } 1129 v->ahash_reqsize = sizeof(struct ahash_request) + 1130 crypto_ahash_reqsize(v->tfm); 1131 1132 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1133 if (!v->root_digest) { 1134 ti->error = "Cannot allocate root digest"; 1135 r = -ENOMEM; 1136 goto bad; 1137 } 1138 if (strlen(argv[8]) != v->digest_size * 2 || 1139 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1140 ti->error = "Invalid root digest"; 1141 r = -EINVAL; 1142 goto bad; 1143 } 1144 root_hash_digest_to_validate = argv[8]; 1145 1146 if (strcmp(argv[9], "-")) { 1147 v->salt_size = strlen(argv[9]) / 2; 1148 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1149 if (!v->salt) { 1150 ti->error = "Cannot allocate salt"; 1151 r = -ENOMEM; 1152 goto bad; 1153 } 1154 if (strlen(argv[9]) != v->salt_size * 2 || 1155 hex2bin(v->salt, argv[9], v->salt_size)) { 1156 ti->error = "Invalid salt"; 1157 r = -EINVAL; 1158 goto bad; 1159 } 1160 } 1161 1162 argv += 10; 1163 argc -= 10; 1164 1165 /* Optional parameters */ 1166 if (argc) { 1167 as.argc = argc; 1168 as.argv = argv; 1169 1170 r = verity_parse_opt_args(&as, v, &verify_args); 1171 if (r < 0) 1172 goto bad; 1173 } 1174 1175 /* Root hash signature is a optional parameter*/ 1176 r = verity_verify_root_hash(root_hash_digest_to_validate, 1177 strlen(root_hash_digest_to_validate), 1178 verify_args.sig, 1179 verify_args.sig_size); 1180 if (r < 0) { 1181 ti->error = "Root hash verification failed"; 1182 goto bad; 1183 } 1184 v->hash_per_block_bits = 1185 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1186 1187 v->levels = 0; 1188 if (v->data_blocks) 1189 while (v->hash_per_block_bits * v->levels < 64 && 1190 (unsigned long long)(v->data_blocks - 1) >> 1191 (v->hash_per_block_bits * v->levels)) 1192 v->levels++; 1193 1194 if (v->levels > DM_VERITY_MAX_LEVELS) { 1195 ti->error = "Too many tree levels"; 1196 r = -E2BIG; 1197 goto bad; 1198 } 1199 1200 hash_position = v->hash_start; 1201 for (i = v->levels - 1; i >= 0; i--) { 1202 sector_t s; 1203 v->hash_level_block[i] = hash_position; 1204 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1205 >> ((i + 1) * v->hash_per_block_bits); 1206 if (hash_position + s < hash_position) { 1207 ti->error = "Hash device offset overflow"; 1208 r = -E2BIG; 1209 goto bad; 1210 } 1211 hash_position += s; 1212 } 1213 v->hash_blocks = hash_position; 1214 1215 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1216 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1217 dm_bufio_alloc_callback, NULL); 1218 if (IS_ERR(v->bufio)) { 1219 ti->error = "Cannot initialize dm-bufio"; 1220 r = PTR_ERR(v->bufio); 1221 v->bufio = NULL; 1222 goto bad; 1223 } 1224 1225 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1226 ti->error = "Hash device is too small"; 1227 r = -E2BIG; 1228 goto bad; 1229 } 1230 1231 /* WQ_UNBOUND greatly improves performance when running on ramdisk */ 1232 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); 1233 if (!v->verify_wq) { 1234 ti->error = "Cannot allocate workqueue"; 1235 r = -ENOMEM; 1236 goto bad; 1237 } 1238 1239 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1240 v->ahash_reqsize + v->digest_size * 2; 1241 1242 r = verity_fec_ctr(v); 1243 if (r) 1244 goto bad; 1245 1246 ti->per_io_data_size = roundup(ti->per_io_data_size, 1247 __alignof__(struct dm_verity_io)); 1248 1249 verity_verify_sig_opts_cleanup(&verify_args); 1250 1251 return 0; 1252 1253 bad: 1254 1255 verity_verify_sig_opts_cleanup(&verify_args); 1256 verity_dtr(ti); 1257 1258 return r; 1259 } 1260 1261 static struct target_type verity_target = { 1262 .name = "verity", 1263 .version = {1, 8, 0}, 1264 .module = THIS_MODULE, 1265 .ctr = verity_ctr, 1266 .dtr = verity_dtr, 1267 .map = verity_map, 1268 .status = verity_status, 1269 .prepare_ioctl = verity_prepare_ioctl, 1270 .iterate_devices = verity_iterate_devices, 1271 .io_hints = verity_io_hints, 1272 }; 1273 1274 static int __init dm_verity_init(void) 1275 { 1276 int r; 1277 1278 r = dm_register_target(&verity_target); 1279 if (r < 0) 1280 DMERR("register failed %d", r); 1281 1282 return r; 1283 } 1284 1285 static void __exit dm_verity_exit(void) 1286 { 1287 dm_unregister_target(&verity_target); 1288 } 1289 1290 module_init(dm_verity_init); 1291 module_exit(dm_verity_exit); 1292 1293 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1294 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1295 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1296 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1297 MODULE_LICENSE("GPL"); 1298